Updated 2020-04-20 12:59:01
Lake Ontario -> 3.0 Deep Pelagic And Offshore Benthic Zone Goal -> Lake Trout
Reporting Interval
2014 - 2019
Area
Meeting Target?
Meets
Indicator Trend
Upward trend
Confidence?
High
Increasing abundance of stocked Lake Trout across a range of age groups.
During the 2014-2019 reporting period, abundance of immature and adult lake trout has met the indicator with the stock recovering from the historic lows observed during 2005-2008. Mature adult CPUE during this period was similar to the levels experienced during 1999-2004 that were established subsequent to the 1992-1993 stocking cuts. Compared to the abundance measures set in the lake trout restoration plan (Lantry et al. 2014), the CPUE of mature females ≥4000g is above target in U.S. waters and near the target in Canadian waters.
Abundance of lake trout (CPUE = Catch per overnight gill net set) in U.S. (US) and Canadian (CA) waters of Lake Ontario. US CPUE calculated from catches made with gill nets set in U.S. waters of Lake Ontario, during September 1983-2019. US CPUE was calculated based on four nets set per site at sites evenly distributed from the Niagara River to Cape Vincent. CA CPUE was calculated from catches in gill net sets in the Canadian portions of Lake Ontario in July and August from 1992 to 2019. To account for varying effort between sites the mean CUE was calculated for each gill net area before calculating the global mean.
Abundance (CPUE = Catch per overnight gill net set) of mature female lake trout ≥4000g in U.S. (US) and Canadian (CA) waters. US CPUE calculated from catches made with gill nets set in U.S. waters of Lake Ontario, during September 1983-2019. CA CPUE was calculated from catches in gill net sets in the Canadian portions of Lake Ontario in July and August from 1992 to 2019. The dashed lines represent the target CPUEs from Schneider et al. (1997) and Lantry et al. (2014).
Methodology
NY Gill Net Index
During September 2014-2019, adult lake trout were collected with gill nets at random transects within each of 14 to 15 geographic areas distributed uniformly within U.S. waters from the Niagara River to Cape Vincent (Elrod et al. 1995; Lantry et al. 2019). Effort varied occasionally due to thermocline depth and vessel availability. Survey gill nets consisted of nine, 15.2- x 2.4-m (50 x 8 ft) panels of 51- to 151-mm (2- to 6-in stretched measure) mesh in 12.5-mm (0.5 in) increments. In general, four survey nets were fished along randomly chosen transects, parallel to depth contours beginning at the 10ºC (50ºF) isotherm and proceeding deeper in 10-m (32.8-ft) increments. A stratified catch per unit effort (CPUE) was calculated using four depth-based strata, representing net position from shallowest to deepest. The unit of effort was one overnight set of one net. Depth stratification was used because effort was not equal among years and catch per net decreased uniformly with increasing depth below the thermocline (Elrod et al. 1995). For all lake trout captured, total lengths and weights were measured, body cavities were opened, and prey items were removed from stomachs, identified, and enumerated. Presence and types of fin clips were recorded, and when present, coded wire tags (CWTs) were removed. Sex and maturity of lake trout were determined by visual inspection of gonads. Sea lamprey (Petromyzon marinus) wounds on lake trout were counted and graded according to King and Edsall (1979) and Ebener et al. (2006).
ON Gill Net Index
Adult abundance indices were derived from a subset of gill nets from a broader, fish community-based sampling program conducted from July to September (Hoyle 2015). Because the program does not specifically target lake trout spatial and thermal selection of sites has been used to provide a comparable index of lake trout (Brenden et al., 2011) however the current data set includes a broader geographical distribution and temperature range to utilize a data from an expanded gill net survey.
Other Resources
Connerton,M.J.. and Eckert, T. H. 2019. 2019 Lake Ontario fishing boat survey. Section 2 In 2019 NYSDEC Annual Report, Bureau of Fisheries Lake Ontario Unit and St. Lawrence River Unit to the Great Lakes Fishery Commission’s Lake Ontario Committee.
Lantry, B. F., Lantry, J. R. and Connerton, M. J. 2019. Lake trout rehabilitation in Lake Ontario, 2017. Section 5 In 2017 NYSDEC Annual Report, Bureau of Fisheries Lake Ontario Unit and St. Lawrence River Unit to the Great Lakes Fishery Commission Lake Ontario Committee.
Lantry, J., Schaner, T., and Copeland T. 2014. A management strategy for the restoration of lake trout in Lake Ontario, 2014 Update. Available from http://www.glfc.org/lakecom/loc/lochome.php [accessed 03 March 2015].
Schneider, C. P., Schaner, T., Orsatti, S., Lary, S. and D. Busch. 1997. A management strategy for Lake Ontario lake trout. Report to the Lake Ontario Committee.
Contributing Author(s)
- Brian F. Lantry - U.S. Geological Survey (USGS)
- Jeremy P. Holden - Ontario Ministry of Natural Resources and Forestry (OMNRF)
- Michael J. Connerton - New York State Department of Environmental Conservation (NYSDEC)
- Dimitry Grosky - USFWS Lower Great Lakes Fish and Wildlife Conservation Office